Metals have high conductivity and therefore are suitable for use in a material for a conductive layer. But at the same time, the metals intensely reflect visible lights, and are unsuitable for use in applications such as touch panel applications, in which a visible electrode pattern is considered as a critical defect. Therefore, a transparent conductive oxide such as ITO (Indium Tin Oxide) has been used conventionally in such applications.
Meanwhile, a metal, which has advantages including patterning easiness, excellent flexibility, and low resistance over the oxide, has been studied as an alternative to the ITO. In recent years, it has been found that the problem of the visible metal wiring can be reduced to some extent by thinning the metal wire or by modifying the pattern.
Conventional technologies for thinning the metal wire include a technology containing using a metal nanowire in a transparent conductive film as described in Japanese Laid-Open Patent Publication No. 2009-505358 (PCT) etc. and a technology containing, utilizing a photographic material technology, exposing and developing a photosensitive material having a silver salt emulsion layer to produce a transparent conductive film. However, in the technologies, the electrical resistance of the resultant wiring is higher than the inherent resistance of the metal disadvantageously, e.g. because a large number of contact points are formed between fine metal particles.
To solve this problem, technology development has been actively studied on a calender treatment (Japanese Laid-Open Patent Publication No. 2009-004726), a photo-fusion treatment (Journal of Electronic Materials, 2011, 40, 2268-2277, J. S. Kang, J. Ryu, H. S. Kim, H. T. Hahn, Sintering of Inkjet-Printed Silver Nanoparticles at Room Temperature Using Intense Pulsed Light), and the like. However, these treatments are disadvantageous in that metallic reflection is enhanced to make a conductive film pattern further visible.
For example, as a technology for making the conductive film pattern less visible, Japanese Laid-Open Patent Publication No. 2011-082211 discloses a method for preventing the reflection from the conductive pattern, which contains stacking a blackening layer having a thickness of 0.01 to 0.5 μm on a surface of a conductive pattern layer. However, in the technology of Japanese Laid-Open Patent Publication No. 2011-082211, conductivity reduction cannot be avoided in principle disadvantageously. Incidentally, a technology for giving an antiglare function to an antireflection film has been known (see Japanese Laid-Open Patent Publication Nos. 2005-070435 and 2004-004404).